Electrical

Electrical Questions? Ask an Electrician Online.

Ask an Expert,
Get an Answer ASAP!

Electrical

Powering rv sites in a rv park expansion, load calculations

Customer Question
powering rv sites in a...
powering rv sites in a rv park expansion
JA: Sometimes electrical issues that that you think will be really complicated end up being easy to fix. The Electrician I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so we can help you best.
Customer: load calculations for medium size RV sites and extra-large rv sites
JA: Is there anything else the Electrician should be aware of?
Customer: yes
JA: What else should I tell the Electrician?
Customer: the owner of the park is asking to power the medium-size sites with a nominal service of 100 Amp and an actual of 50 Amp (204 V/1 Ph), but for the large or extra-large sites he wants 100 Amp nominal and 100 Amp actual . When I read table 551.73 on NEC, I do not get these same recommendations. If I listen to the owner, the size of the service is considerably higher than if I calculate it with the NEC.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Electrician about your situation and then connect you two.
Submitted: 1 year ago.Category: Electrical
Show More
Show Less
Ask Your Own Electrical Question
Answered in 32 minutes by:
2/29/2016
Electrician: Kevin, Licensed Electrical Contractor replied 1 year ago
Kevin
Kevin, Licensed Electrical Contractor
Category: Electrical
Satisfied Customers: 3,792
Experience: 31 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License
Verified

Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.

1) I agree with you. Nowhere within Article 551 does it state that RV sites must have 100 amp feeders. The NEC only states 20 amp, 30 amp and 50 amp sites. 100 amp feeder sites would be considered as "optional" in my code interpretation.

2) Article 551.71 (Type Receptacles Provided) states that a percentage of the total sites must be a mixture of the various feeder amperages.

3) Table 551.73(A) Demand Factors would also be applicable when calculating the site feeder and service entrance conductors.

Ask Your Own Electrical Question
Electrician: Kevin, Licensed Electrical Contractor replied 1 year ago

If you have any additional questions, just let me know and I’ll be glad to answer them for you.

Otherwise, don’t forget to rate me before you log Off.

Thanks.................Kevin:)

Ask Your Own Electrical Question
Customer reply replied 1 year ago
Hello Kevin:
So what is your recommendation for the extra-large sites. For the medium sites, I have: 5 straight runs of 17 sites, 1 straight run of 16 sites, and 1 straight run of 15 sites. For the large and extra-large sites, I have 1 straight run of 9 sites, 1 straight run of 16 sites, and 1 straight run of 21 sites.All sites have a power tower comprised of (1) 20-Amp 1-pole breaker, (1) 30-Amp 2-pole breaker, and (1) 50-Amp 2-pole breaker.For the medium sites, I can run a feeder from a 200 Amp breaker to feed a group of 4 sites, or a 250 Amp breaker for 5 sites.
What would you do with the large and extra large? 200 Amp for 2 sites?..F.
Electrician: Kevin, Licensed Electrical Contractor replied 1 year ago

1) Yes, installing either a 200 amp or a 250 amp feeder will satisfy the 50 amp sites.

2) For the medium sites you will have no other choice but to 1st satisfy article 551.71 (percentage breakdown on receptacle types) and then apply the demand factors.

3) I would then apply article 551.73 (D) Feeder circuit capacity. and calculate the larger sites (100 amp) separately and then apply the demand factor table. Since the total number of large sites = 46, use a demand factor of 41% ------> (36 plus sites) as shown in table 551.73(A).

4) Then total the 2 load calculations from above and size the service based on these 2 load calc's. By separating the 2 load calc's and then totaling them, this will satisfy 551.73(D).

Your thoughts?

Ask Your Own Electrical Question
Electrician: Kevin, Licensed Electrical Contractor replied 1 year ago

1) Since the RV park owner is requesting for 100% demand on each of the 100 amp sites, that's gonna be a large increase on the total park service, not to mention your individual feeder runs. I recommend to show the customer article 551.73 and explain that the probability of all sites being filled to capacity and all using 100 amps each and simultaneously is highly unlikely. Thus the reason why the NEC developed the demand table.

Ask Your Own Electrical Question
Customer reply replied 1 year ago
The problem is that all the extra large sites run the heating during the night. If you read the fine print notes FPN on the bottom of 551.73(C). It says (I use NEC 2002) that he demand factor may be inadequate in extreme weather areas. When the park has no extra large vacancies, the breakers trip. I need give them more than the 41% that you mentioned above. But the question is how much. If you go back to my listing, each straight run has its own panel, or I can add one if they don't already have it. This means that the demand factor is for fewer than 36-plus units. Also, if you read 551.73(A), what does "supply facility" mean? a power supply tower unit next to each RV? If that is the case, what load should I assume for each one of these stations? 9600 VA? or is this load for the 50 Amp breaker only? the power supply tower station does not have only a 50 Amp breaker but also a 30 Amp and a 20 Amp. So what load is the actual basis of calculation.
Electrician: Kevin, Licensed Electrical Contractor replied 1 year ago

Thanks for the replies.

1) Where the tower has more than 1 receptacle, the calculated load shall be calculated only for the highest receptacle. If a 50 amp breaker, then the 9600 VA value will be used. 9600 VA will the basis of calculation per 551.73(A).....ie.......last sentence in the 1st paragraph (highest rated receptacle).

2) Yes, the supply facility will be the tower (the plug-in pedestal) located next to each RV site.

3) I'm using the 2011 NEC and it also shows the FPN for extreme hot or cold temperatures. In consideration of the FPN and this being a case-by-case basis. I would ask the RV owner to quantify the average site capacity or future site capacity during the summer and winter months. Logically, I would start out by splitting the 36 sites by 50% down to 18 sites, thus increasing the demand factor from 41% to 47% as a minimum. This will provide an increase in amps. Once again, in cases such as this, I think obtaining an average capacity during the summer and winter months would be in order and appropriate to confirm from the park owner. So the $64K question for the owner is "will all 46 of the large sites be utilized all of the time" during summer and winter months? I doubt it:)

Keep in mind, you can only design the electrical distribution system based upon the NEC requirements as well as the estimated loads. How many RV rigs that stay in the park are going to have 240 volt electric hot water heaters, 240 volt electric dryers, 240 volt ranges, 240 volt heaters, etc. all running simultaneously? Far and few in between will have these amenities in my opinion. For example, even a 100 amp service on a 1700 sq feet house with electric appliances will only pull an average of high 80 or low 90 amps in most cases under average Full Load.

Ask Your Own Electrical Question
Ask Kevin Your Own Question
Kevin
Kevin
Kevin, Licensed Electrical Contractor
Category: Electrical
Satisfied Customers: 3,792
3,792 Satisfied Customers
Experience: 31 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License

Kevin is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future.

JimmyBagley, IA

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Mike

Mike

Master Electrician

1,425 satisfied customers

Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer

Jason

Jason

Service Technician

3,940 satisfied customers

Over 20 years of experience in all types of installations, troubleshooting, and repairs.

Mike G.

Mike G.

Master Electrician

7,603 satisfied customers

Proven Professional 48 years Experience

Kevin

Kevin

Licensed Electrical Contractor

3,792 satisfied customers

31 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License

AssuredElectrical

AssuredElectrical

Master Electrician

3,264 satisfied customers

Contractor-42+ Years in the ElectricalTrade

electrifier

electrifier

Master Electrician

1,458 satisfied customers

Electrical contractor and electrical inspector for over 24 years with phone and networking expertise

Rich

Rich

Master Electrician

1,115 satisfied customers

Over 35 years residential, commercial, industrial wiring, install, troubleshoot, service, maintain

< Previous | Next >

Related Electrical Questions
Backstory: I am closing on the purchase of a house, however,
Backstory: I am closing on the purchase of a house, however, the home is feeding power to an adjacent property. I want this shut off, but also removed completely from end to end. I am concerned the ne… read more
Mike G.
Mike G.
Master Electrician
Vocational, Technical or Trade Scho
7,603 satisfied customers
Installing an Cadet Soft Heat 220 V baseboard heater in a
Installing an Cadet Soft Heat 220 V baseboard heater in a four season porch. I've been told code is to use a GFCI breaker. So I installed a 220 GFCI breaker in the box (still turned off), but the base… read more
Sam I
Sam I
Electrician
B.S.
366 satisfied customers
I have a ej500 switch and there are 3 wires, red, blue, and
Hi.... I have a ej500 switch and there are 3 wires, red, blue, and black... … read more
Mike G.
Mike G.
Master Electrician
Vocational, Technical or Trade Scho
7,603 satisfied customers
I have 2 3wire with ground running into a light box. my
I have 2 3wire with ground running into a light box. my neighbor removed the light but dosent remember how they go back together. the light is on 2 3way switches, but ive never seen the travelers come… read more
George Smith
George Smith
Vocational, Technical or Trade School
273 satisfied customers
MAZON Harbor Breeze 3 blade ceiling fan, w/remote, 44", Need
MAZON Harbor Breeze 3 blade ceiling fan , w/remote, 44", Need replacement BULB … read more
David Bowden
David Bowden
Owner
330 satisfied customers
I have a 22.5 cu in plastic box and want to put 2 14-3 and 2
I have a 22.5 cu in plastic box and want to put 2 14-3 and 2 14-2 wires plus a 3 way switch in, is this ok … read more
Sam I
Sam I
Electrician
B.S.
366 satisfied customers
I am planning to install an electrical subpanel. Laundry
I am planning to install an electrical subpanel. Laundry facilities are being moved out of a double wide mobile home and into a newly built small structure adjacent to the double wide mobile home. The… read more
Sam I
Sam I
Electrician
B.S.
366 satisfied customers
I have a 1.5 hp motor 3 phase 480 and im trying to wire a
hi i have a 1.5 hp motor 3 phase 480 and im trying to wire a drum switch to it and needed some guidance … read more
Sam I
Sam I
Electrician
B.S.
366 satisfied customers
I would like to run a 30 amp extension from the dryer outlet
I would like to run a 30 amp extension from the dryer outlet to run a 30 amp heater in the garage. The dryer is 4 wire with ground and the heater is 3 wire with ground. Both are 30 amps.I understand t… read more
Sam I
Sam I
Electrician
B.S.
366 satisfied customers
A space heater killed my outlets how much will it cost to
A space heater killed my outlets how much will it cost to fix them … read more
Mike G.
Mike G.
Master Electrician
Vocational, Technical or Trade Scho
7,603 satisfied customers
This is so weird... I turned on the light/fan in my bedroom,
This is so weird... I turned on the light/fan in my bedroom, the lightswitch sparked and the lights on the fan went out, but the fan still worked. My husband replaced the switch and the lights worked … read more
Mike G.
Mike G.
Master Electrician
Vocational, Technical or Trade Scho
7,603 satisfied customers
I need a wiring diagram to install new safety photo eyes at
I need a wiring diagram to install new safety photo eyes at the bottom of my garage door. The previous owner had removed the original ones. Craftsman 1/2 h.p. 41A5021-2E date 02/01 132C2105-3B… read more
Jason
Jason
Service Technician
Associate Degree
3,940 satisfied customers
Im trying to install a decora smart dimmer switch. 2 hour. I
I wired it black to black white to white and the ground to the box… read more
Mike G.
Mike G.
Master Electrician
Vocational, Technical or Trade Scho
7,603 satisfied customers
I'm planning to supply power to 34 more sites on our rv
I'm planning to supply power to 34 more sites on our rv park. Supply 50 amp service to all. Covering 400 ft to 90 ft area approximately. Planning to build a power house at one end of the 400 ft rectan… read more
Mike G.
Mike G.
Master Electrician
Vocational, Technical or Trade Scho
7,603 satisfied customers
Is it code to have a three pole 20 amp breaker which
Is it code to have a three pole 20 amp breaker which supplies multiple receptacles on a commercial job? … read more
Mike G.
Mike G.
Master Electrician
Vocational, Technical or Trade Scho
7,603 satisfied customers
The ceiling fan leaks power into pull chains. I have
The ceiling fan leaks power into pull chains. I have disconnected the fan, put it on the table and used an old appliance cable. Reconnect all wires to fan and plug it in an outlet. I have the same pro… read more
George Smith
George Smith
Vocational, Technical or Trade School
273 satisfied customers
I am installing a GE Oven/Microwave combination, model#
I am installing a GE Oven/Microwave combination, model# ***** rated at 7.2kW @ 240V. I currently have a 30A breaker feeding 240V via 10/3 wiring. The GE spec calls for a 30A breaker @ 240V. Question i… read more
Sam I
Sam I
Electrician
B.S.
366 satisfied customers
I'm installing a solar array and need to know the size wire
I'm installing a solar array and need to know the size wire to run from the 80 amp sub panel at solar array to the main breaker box / disconnect. The run is about 200 feet. I expect to install the wir… read more
Wayne Roberts
Wayne Roberts
Electrical Trade
85 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x